Hair generally is formed with a cuticle (the outer layer), a cortex (an inner layer), and a medulla (the innermost layer). The spiraling nature of naturally curly hair, particularly black hair, is caused by the shaft of the hair having a flat cross-section. Additionally, the cuticle of the hair serves to maintain the curly nature of the hair through a thick and durable covering of keratin proteins.
It has often been a desire of people having curly hair to straighten their hair, such as by combing and/or brushing the hair. A number of combs have been designed specifically for use with curly hair, such as the Afro pick, and a comb having holes along the spine of the comb to allow the hair a space to turn and unwind. Despite these straightening actions, however, the hair is only pulled straight for an instant, and due to the curly nature of the hair, the hair returns to its original curvature.
In order to keep the hair in a straightened state, a chemical relaxer is often applied to the hair. Chemical relaxers typically consist of a strong alkaline chemical, such as lye, and require that hair care technicians exhibit a great deal of caution in order to avoid damaging the hair, or burning the scalp of the person being treated. Moreover, due to the harshness of the chemical relaxers, it is important that the chemicals are only left on the hair for a limited period of time. In fact, chemicals left on the hair too long may even result in the hair breaking.
As an alternative to the chemical straighteners, the hair may be straightened by pressing and curling the hair. Pressing includes the application of extreme heat to the hair in order to “press out” the curls. One device used in the pressing process is a pressing comb, also known as the straightening comb. The pressing comb is made of a heavy metal and formed with a single row of teeth. The heavy metal material allows for the comb to be heated, such as by placing the comb in a heating device, and then retains the heat during the combing process. In this manner, the hair is heated and combed straight at the same time, resulting in the hair remaining in its straightened state. However, with moisture, the hair will revert back to its natural, curly state, necessitating the hair being straightened again. Consequently, it is possible that a person having curly hair could need to straighten their hair several times a week.
Another method used for straightening hair, for example, is where the user may employ a hair brush to place tension on his or her hair while applying heated air with a hair dryer. In particular, the user gathers a portion of hair and extends it away from his or her head. The extended hair portion is then treated with heated air to enable it to retain its extended shape. However, the heated air is often insufficient to adequately dry the hair to maintain it in a straightened condition.
In another similar method, a blow dryer nozzle having two rows of teeth is used. The teeth are separated to allow the air from the blow dryer to flow between the teeth to heat the hair during the combing process. While this nozzle provides localized heating for the rapid evaporation of any moisture within the hair, it is considerably cooler than the straightening comb, and therefore does not provide the same straightening effect.
U.S. Pat. No. 5,729,907 describes an attachment for a hair dryer containing on its upper section a curved heat transmitting plate with a comb extending from one side. The heat transmitting plate has a significant surface area and thus requires spaced ridges to prevent contact of scalp and fingers with the heat transmitting plate.
U.S. Pat. No. 6,009,883 discloses an improved blow dryer nozzle having two parallel rows of teeth disposed on opposite sides of the nozzle with a steel heating bar situated between the two rows of teeth. The steel heating bar extends slightly higher than the base of the teeth for striking the hair within the teeth. As the hair passes over the heating bar, the heated bar straightens the hair, much like the effects of using a traditional straightening comb.
Thus, the main concern of improvements to hair dryers was to enable the blower to supply sufficient hot air to dry the hair quickly. However, it is often desired to cool the hair right after having shaped it with the heated air from the blower nozzle. A common method of cooling the hair while being shaped with a round brush is to reverse the hair dryer and place the air intake against the hair on the brush. This sucks room temperature air through the hair to cool them. This method, although widespread, is not very efficient in that the suction is quite weak and takes long to dry the hair.